Data migration is the transferring of data between storage subsystem types, formats, or computer systems. These systems, types, or formats can be similar or dissimilar. Migration is usually performed under program control to try to make movement of data as complete and as automated as possible. Data migration is needed when you change computer systems or upgrade to new products. As with any data center change, you want to avoid disrupting or disabling active applications while still achieving an efficient migration. Compressing and uncompressing data may utilize a large number of computer resources.